Transferring hard drives from one NAS to another

I currently have a 2-bay Asustor (AS1102TL). Both bays currently have an 8TB hard drive with the entire setup formatted as JBOD. I'm starting to run out of storage capacity and I have access to a 4-bay AS1104T and some additional hard drives that can expand my total storage capacity.

Is there a way I can just take the current two hard drives and drop them into the 4-bay without having to reformat them or lose the content?

Is it possible to add more hard drives later to expand the total storage or does all of the partitioning need to happen when the NAS is being set up? My previous NAS allowed for this and I am fairly sure the Asustor one can do the same but just wanted to check with more experienced users for confirmation.

Much appreciated in advance.